川中磨溪气田嘉陵江组“土黄色”粉晶云岩成因及其储集层形成机制  

Genesis and dolomitization of “Khali” powder crystal dolomite in Triassic Jialingjiang Formation,Moxi gas field,central Sichuan Basin,SW China

作　　者：唐浩[1] 谭秀成[1,2] 刘宏[2] 周彦[2] 李凌[2] 丁熊[2] 唐青松[3] 邹娟[4] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室 [2]西南石油大学地球科学与技术学院 [3]中国石油西南油气田公司川中油气矿 [4]中国石油西南油气田公司川西北气矿

出　　处：《石油勘探与开发》2014年第4期504-512,共9页Petroleum Exploration and Development

基　　金：国家重点基础研究发展计划(973)项目(2012CB214803);中国石油科技创新基金项目"滩相碳酸盐岩储集层成因机理及预测模型研究"(2011D-5006-0105)

摘　　要：以川中磨溪气田嘉陵江组二段2亚段B层为例,系统剖析"土黄色"粉晶白云岩储集层的基本特征,讨论"土黄色"粉晶白云岩成因和储集层形成机制。测录井及取心资料分析发现,粉晶白云岩主要储集空间为晶间溶孔和晶间孔,喉道以片状为主,孔喉配置关系较好,表现出中孔低渗特征,为孔隙型储集层。白云岩成因分析发现,白云石化作用发生于成岩早期,其空间演化规律明显,垂向上自上而下白云石化程度逐渐变差,横向上随着远离卤水源白云石化程度逐渐减弱,存在过白云石化现象,渗透回流远端白云岩物性优于紧邻卤水源白云岩,说明"土黄色"粉晶云岩为渗透回流白云石化成因。储集层形成机制分析表明,白云石化作用形成的晶间孔隙为后期储集层改造提供了优质渗流通道,早期喀斯特岩溶作用对晶间孔的扩溶改造是优质储集层形成的根本原因。Taking the B bed of the second submember of the second member of Triassic Jialingjiang Formation in Moxi gas field as an example, the basic characteristics and controlling factors of the ＂Khali＂ powder dolomite reservoir is analyzed systematically, and the genesis and forming mechanism of the powder crystal dolomite are examined. Logging and core analysis show that the reservoir has intercrystalline pores and intercrystalline dissolved pores as the main storage space, mainly lamellar throats, good configuration between pores and throats, and medium porosity and low permeability, representing typical porous-type reservoir. Dolomitization genesis analysis indicates that dolomitization occurred in the early diagenetic stage, with obvious spatial evolution pattern, the degree of dolomitization decreases gradually from top to bottom, and decreases with the increase of distance from the source of brine horizontally; over-dolomitization occurs in the study area, the petrophysical property of dolomite close to the source of brine is worse than the dolomite formed by seepage-reflux far from the source of brine, which suggests the ＂Khali＂ powder crystal dolomite is of seepage-reflux genesis. Reservoir genesis analysis shows that the intercrystal pores formed by seepage-reflux dolomitization acted as superior seepage channels for reservoir reformation later, and syndiagenetic karstification is the root cause of the formation of ＂Khali＂ powder crystal dolomite reservoir.

关 键 词：“土黄色”粉晶云岩 渗透回流白云石化作用 喀斯特岩溶 嘉陵江组 磨溪气田 四川盆地 

分 类 号：TE122.1[石油与天然气工程—油气勘探]